This invention relates to the art of motor vehicle transmissions and, more particularly, to an improved method and system for lubricating bushings, gears and the like in such a transmission.
The present invention finds particular utility in conjunction with distributing lubricant in an automatic vehicle transmission to elements therein requiring lubrication and which, due to their location and/or the obstruction of other elements in the transmission are difficult to reach with lubricant. One such element is the rear bushing disposed adjacent the rear end of an extension housing of an automatic transmission for supporting an output shaft, and the present invention will be disclosed and described in detail in conjunction with lubricating such a rear bushing. At the same time, however, as will become apparent hereinafter, the invention is applicable to distributing lubricant to gears, bearings and other elements in a manual or automatic transmission.
As is well known from such prior art patents as U.S. Pat. No. 4,329,887 to Kawamoto and U.S. Pat. No. 4,621,710 to Tsukamoto et al, conventional automotive transmissions include an extension housing extending rearwardly from the main transmission casing or housing for supporting an output shaft and sleeve yoke by means of a bush interposed between the yoke and a bearing portion of the extension housing. Adequate lubrication of the bush has been difficult to obtain because of its location at the rear end of the extension housing, and considerable attention has been devoted to this problem as is demonstrated in part by the foregoing prior art. For example, previous efforts to lubricate the bush have included the provision of a conduit for guiding lubricating oil under pressure from a source located in the main gear case of an automatic transmission directly to the rear bush as shown in Tsukamoto et al, and pumping lubricating oil to a hollow control shaft of a speed change gear in a manual transmission for flow through the control shaft to the rear bush as shown in Kawamoto. These methods and arrangements are disadvantageous for a number of reasons, none the least of which is the cost attendant to special modifications of the extension housing and/or transmission parts and the configuring and installation of specially contoured guide tubing for the lubricant. The rear bush in a transmission such as that disclosed in Sukomoto et al has been lubricated heretofore by a direct spray of lubricant under pressure but, as will be appreciated from the latter patent, such requires the extension housing to be devoid of any interfering parts between the lubricant outlet and the bush. Furthermore, other prior art systems which rely on gravity flow of lubricant along ribs, channels or the like on the interior of the extension housing are subject to the further disadvantage that there are periods when lubricant does not flow to the rear bush, such as when the vehicle is travelling downhill.